This section provides background information related to the present disclosure which is not necessarily prior art.
A typical automotive engine is a four-cycle internal combustion device which includes an engine block having multiple cylinders. Each cylinder supports a piston for reciprocating movement. A cylinder head is coupled to a top surface of the engine block such that the block and head define a combustion chamber. The cylinder head includes a set of intake ports and a set of exhaust ports for each cylinder which, in combination with the intake valves and exhaust valves, allow combustion gases to enter and exit the combustion chambers. An intake manifold and an exhaust manifold are typically coupled to the cylinder head for routing the combustion gases to and from the intake and exhaust ports.
It is common for a portion of the exhaust gases exiting the combustion chamber to be recirculated through an exhaust gas recirculation or EGR valve to the intake manifold or intake ports. An automotive engine may also be configured with a turbocharger having a turbine or scroll which is driven by the exhaust gases and/or may have a catalytic converter for exhaust gas treatment. As such, these components must also be in fluid communication with the exhaust ports.
It is important to locate these components as close as possible to the exhaust manifold. However, other engine components (e.g., valve train, fuel injection, air filters, alternator) and vehicle systems (e.g., transmission, power steering, front suspension, air condition compressor, etc.) must also be located adjacent the engine under the hood of the vehicle. Accordingly, the packaging space for these components can be extremely limited.
In a four-cylinder engine designed for running in dedicated exhaust gas recirculation mode, one cylinder is capable of supplying exhaust gas recirculation to all four cylinders. Thus, it may be desirable to separate the exhaust manifolding of this cylinder from the remaining three cylinders. Typically this design requires a single complex stainless steel manifold or two separate stainless steel manifolds.